The Specific Aims of the Protein Core are to provide instrumentation, methodological development, experimental training, and technical support in protein microchemistry, protein expression, protein purification, and sample preparation for protein structure determination, as required for the Projects of this Program Project. In the previous project periods, the Protein Core has concentrated on protein microchemistry, including peptide synthesis and protein microsequencing. In the next project period, it is proposed that the protein Core are: 1. To express proteins of interest in signal transduction in the cardiovascular system at high level in bacterial, viral, or yeast expression systems, as needed in the Projects of this Program Project; 2. To efficiently purify proteins expressed in bacterial, viral, or yeast expression systems in high yield, with or without epitope tags, as needed in the Projects of this Program Projects; and 3. To prepare protein samples for determination of three-dimensional structure, including labeling with stable isotopes for NMR analysis and crystallization for x-ray diffraction analysis, as needed in the Projects of this Program Project.